Electric-furnace resistor



O. A. COLBY April '14, 1925. 1,533,231

ELECTRI C FURNACE RES I STOR Filed Dec. 2 1922 Fig.1.

INVENTOR Ova A. Coil aya- PatentdlApr. 14, 1925.

ORA A. COLBY, or IRWIN.

1 ,533,231- FFlC E.-

PENNSYLVANIA, A SSIGNOR TO WESTINGHO USE ELECTRIC MANUFACTURING CQMIPANY, A'CORPOEATION OF PENNSYLVANIA.

fluorine-FURNACE RESISTOR.

Application filed. December 2, 1922. Serial no. 604,567.

To all 207mm it may concern v Beit known that I, ORA Corinna citizen ofthe United States, and a resident of Irwin, in the county of lVestm'orela-nd and State of Pennsylvania,.have invented a new and useful Improvement in Electric-Furnace Resistors, 0f Which-the following is a specification.

My invention relates to electric furnaces and particularly to electric resistance furnaces. 1

The object ofmy invention is to provide a relatively simple, compact and rugged electric heating element for an electricresistance furnace.

In practicing my invention, I provide a. plurality of relatively thin, flat, refractory," electrical-conducting plates of substantiallyrectangular cross-section alternating with a plurality of refractory electrical conducting bars of substantially I-beam section with their flat surfaces in operative engagement.

Spaced refractory, electric-insulating, supporting plates operatively engage certain of said flat plates-to maintain, the heating element in its proper operative position within a furnace chamber. Suitable resilient compressing means is provided to maintain the refractory electrical conducting elements in close operative engagement. a

In the single sheet of drawings,

Figure 1 isa view, in longitudinal vertical section, of an electric furnace comprising the device embodying my invention,

Fig. 2 is a view, in perspective, of one of therefractory members comprising a part of the heating element."

Fig. 3 is a view, in perspective, of a flat bar comprising another member of the heat ing element, and- I Fig. 4 is a view in perspective of a refractory electric-insulating supporting member. An electric furnace 11 comprises an outer metallic casing 12 having suitable supporting members '13 secured thereto. An outer lining 14 comprises a plurality of bricks or blocks of a suitable refractory heat-insulating material. An inner lining 15 con'iprises a plurality of bricks or blocks of a suitable refractory high-temperature resisting material. The bricks or blocks comprising the two linings are so disposed as to provide a furnace chamber 16 of any suitable or .desired contour and dimensions.

A heating element 17 for the furnace comunder 'pressure, threaded rod 26,

' fractory,

. iris es a plurality of elongated fiat plates or bars 18, alternating with a plurality of refractory electric conducting bars 19, of sub: sta-ntially I-bea'm section; The height of the plates or bars 18 is such as to permit of the plates 18 being located within the overhanging flange portions of the members 19' withthe flat surfacesof the respective mem= .bers in close operative engagement.

An elongated refractory conducting elec-' trode 21 extends through a suitable opening 1n the furnace walls at each side thereof, w1th 1ts inner end in operative engagement with one of the plates 18 or an end plate 23.

water-cooled electric-circuit .terminal. member '24 operatively engages the outer tapering end of the electrode21, being provided with a suitable co-operatingopen-ing' therein. An electric-insulating member 25 comprising a ring of asbestos lumber is lo-' cated Within the outer surface of the end walls: of the furnace surrounding the terminal member 24 to prevent leakage of-current therefrom to the furnace structure.

Compressing means for maintaining the terminal member 24.- in close operative-engagement with the electrode 21 and for maintaining the plates and bars 18 and 19 may. comprise a screwthe inner enlarged end of which rests against the outer surface of a block 27 of suitable electric-insulating material, operatively engaging the outer surface of the terminal member 24. A ,helical spring 28 surroundsl the rod 26 over a portion of its length and, has its outer end operatively engaging a fixed member 29, and its inner end engaging a washer 31 resting against an adjusting nut 32 which has screw threaded engagement with the rod 26. While I have illustrated a specific embodiment of a compressing means, I do not desire to be'limited thereto, as any suitable construction of such means may be employed. In order to assist the resilientcompressingmeans hereinbefore, described in supporting the built-up heating element 17 in its proper operative'position within the furnace chamber 16, I

ectric-insulating, thin, at plates 33 which. operativelyengage one or more of the plates 18 in the built up heating element 17.

opening 34 is provided in each of the 11p irovi'dea plurality of'sgaced, re- 1% e tive platesf33 may rest. in order to insure that little or no current shall flowbetween the spaced plates 33 through any circuit other-than that of the built-up heating element.

If desired, the furnace chamber 16 may be divided into a work-receiving compartment and aheating.compartment 37 by a refractory diaphragm 38, which may be supported in the furnace chamber by any suitable means, such as integral portions of the inner lining 15. As this heating element is preferably employed in. furnaces operating at relatively hightemperatures, it; is neces.

sary' to employ carbomvceons material for the plates and bars constituting the heating element and these bars are oxidized by air entering the heating chamber during the operation'of the furnace. Most of the air enters throughthe opening (not shown) into the work-receiving compartment and the use of a refractory diaphragm reduces the oxidizing action of the entering airon'the caraonaceous resistor members. I

As the alternate resistor members are provided with mierhanging flanges, any air entering the heating chamber 37 e'xpends its oxidizing action on the overhanging portions which protect the edges of the flat plates, whereby a; longer life of the built-up heating element is insured. The use of inter mediate, spaced, supporting members makes it possible/to operate with less pressure of the resilient compressing means whereby a higher rcsistanc oi the built-up heating element is secured.

Various modifications and changes in detail and arrangement may be made without departing from the spirit and scope of the invention, and such modifications are intended to be. covered by the appended claims,

I claim as my invention: 1. 1 n'an electric furnace, in combination, a resistor comprising a plurality of retractory electrical-conducting bars, of I-beam section, alternating with relatively thin flat refractory electrical-conducting bars interfitting with said bars of I-beam section and spaced refractory electrical-insulating supporting members operatively engagingsaid thin flat bars to support said resistor.

2. In an electric furnace, in combination, a resistorcomprising a plurality of retrac terry electri'al-condlwting bars, alternately of rectangular and of I-beam section, interlitting and supporting each other, and a plurality of spaced thin refractory plates ope atively engaging certain of said bars to support said resistor.

23. In an' electric furnace, in con'ihination, a resistor comprising a plurality of refractory electrical-conducting bars, alternately of rectangular and of I-beam section, interfitting and supporting each other, a plurality of spaced thin refractory plates ope-ratively engaging certain of said bars to support said resistor and resilient means for maintaining all of said, bars in close operative engagement.

Intest'imony whereof, I have hereunto subscribed my name this 27th day of November, 1922. 01m A. colic-r. 

